bug#45036: Add archive-copy, just like dired-do-copy

["積丹尼 Dan Jacobson" <jidanni@jidanni.org>]

"Zip-Archive mode defined in ‘arc-mode.el’:
Major mode for viewing an archive file in a dired-like way."

That's great, but how about letting "C" copy a file, like in dired.

I mean what's the big deal? We just want to copy it to /tmp, ~, etc.

Sure, raise some alarm if we want to copy it to some place _within the
archive_. But hey, you let us view a file with v, so why not copy with C?

Wait, there's

5 matches for "extract" in buffer: *Help*
     22:e .. f		archive-extract
     25:RET		archive-extract
     35:E		archive-extract-other-window
     45:o		archive-extract-other-window
     56:<mouse-2>	archive-extract

Must be important. Let's have a look.

"In archive mode, extract this entry of the archive into its own buffer."

I don't want to get tangled up (editing?) in the archive.
I don't want to even look at the file's contents.
I just want to copy it somewhere far far away (but still on the local
machine.)

So please add archive-copy or archive-copy-file, that, just like
dired-do-copy, preserves the date.

There I am, looking at

M Filemode      Length  Date         Time      File
- ----------  --------  -----------  --------  -----------------
  -rw-rw-rw-     30933   3-Dec-2020  12:04:16  doc.kml
  -rw-rw-rw-       481   3-Dec-2020  12:04:16  images/icon-1.png
  -rw-rw-rw-       478   3-Dec-2020  12:04:16  images/icon-2.png
  -rw-rw-rw-      1026   3-Dec-2020  12:04:16  images/icon-3.png
- ----------  --------  -----------  --------  -----------------
                 32918                         4 files

with the cursor on doc.kml .

OK, "C" should allow me to copy doc.kml to e.g., /tmp/doc.kml .

emacs-version "27.1"